The present invention relates to a webbing height adjuster used in a seat belt device for a vehicle to adjust the height position of the webbing.
Vehicles such as automobiles are provided with seat belt devices mounted to seats of the vehicles.
A three-point type seat belt device is an example of such conventional seat belt devices. The three-point type seat belt device comprises a shoulder belt for restraining the shoulder, chest, and abdomen of a vehicle occupant, and a lap belt continuously formed with the shoulder belt for restraining the hip of the occupant.
It is desirable that the webbing constituting the seat belt is worn by the occupant in such a position so as to fit the occupant as possible, in order to effectively restrain the occupant in an emergency and to allow the occupant to be in comfort without a sense of oppression. Because the shoulder belt supports the portion from the shoulder to the abdomen through the chest of the occupant, the shoulder belt is particularly desirable to be in such a position so as to fit the occupant. On the other hand, there is a wide variety of people who sits in the seat, such as a child, an adult of big body, an adult of small body and so on, that is, the body sizes of occupants are, of course, different. Therefore, the seat belt device is previously provided with a webbing height adjuster which can adjust the height position of the webbing for each occupant to allow the webbing to fit the occupant.
A webbing height adjuster disclosed in Japanese Patent Publication No. S63-48734 is one of such conventional webbing height adjusters.
As shown in FIG. 11, the webbing height adjuster comprises a guide rail 101 fixed to a vehicle body, a slider 102 slidably fitted to the guide rail 101, a nut 103 fixed to the slider 102, an anchor bolt 104 screwed into the nut 103, a collar 106 fitted to the anchor bolt 104, an anchor plate 107 mounted on the anchor bolt 104 through the collar 106, a through ring 109 fixed to the anchor plate 107 for guiding the webbing 108, a lock spring 110 slidably fitted to the collar 105, a stopper 111 formed together with the lock spring 110, cavities 112 into one of which the stopper 111 is inserted for engaging, a cam 113 slidably fitted to the collar 105 to press the lock spring 110 in the axial direction, and a control lever 114 rotatably fitted to the collar 105 to generate force in the axial direction in cooperation with the cam 113.
In the webbing height adjuster, for adjusting the height position of the webbing, the control lever 114 is rotated so that a collar-contact portion of the lock spring 110 where is in contact with the collar 105 is pressed rightward in this figure by the cam 113, thereby releasing the stopper 111 from one of the cavities 112 to cancel the engagement with the guide rail 101. Therefore, the slider 102 is now slidable relative to the guide rail 101. After moving the slider 102 along the guide rail 101 to a desirable position, the control lever 114 is released so that the cam 113 is pressed leftward by the force of the lock spring 110. Because of the cam action, the control lever 114 is rotated to a nonoperational position and then the cam 113 and the collar-contact portion of the lock spring 110 also moves leftward. Therefore, the stopper 111 is inserted into a corresponding one of the cavities 112 so as to lock the movement of the slider 102. In this manner, the height position of the webbing 108 is adjusted.
By the way, since the locking mechanical components such as the control lever 114, the cam 113, and the lock spring 110 are supported by the anchor bolt 104 which also supports the anchor plate 107, the anchor bolt 104 must have a complex and special configuration, thereby increasing the cost. Moreover, for allowing each component to reliably exhibit its function, it is desirable to increase the accuracy of each component since a plurality of components intervene the anchor bolt 104, thereby further increasing the cost.
Since the anchor bolt 104 should be provided with not only a plurality of components arranged in the axial direction but also a margin for allowing the axial movement of the collar-contact portion of the lock spring 110 and the cam 113, the anchor bolt 104 must be long in the axial direction. This makes the webbing height adjuster relatively thick.
To overcome such problems, a webbing height adjuster which supports locking mechanical components not by an anchor bolt supporting an anchor plate is proposed in Japanese Utility Model Publication No. H7-6036.
As shown in FIG. 12, for adjusting the height position of the webbing in the webbing height adjuster of this publication, a fixing knob 115 and an operational knob 116 are pressed inwardly by grasping them so that an operational member 117 relatively moves downward in this figure relative to a slide plate 118. The relative movement of the operational member 117 makes a stopping piece 119 come into contact with a release lever 120 and presses the release lever 120 so that the release lever 120 is displaced to a position shown by two-dot lines. The displacement of the release lever 120 release a slide lock mechanism so as to allow the movement of a slider 121 along a rail 122. Therefore, the position of an anchor 123 can be adjusted by moving the slider 121 up and down with grasping the both knobs 115 and 116. After adjusting, the both knobs 115 and 116 are released from the grasped state so that the operational member 117 relatively moves upward relative to the slide plate 118 due to the biasing force of the spring 112. Therefore, the release lever 120 returns to the original position and slide lock mechanism locks the slider 121 and the anchor 123 from moving from this position.
In this manner, the height position of the webbing 124 can be adjusted to a suitable position corresponding to the body size of the occupant.
In the webbing height adjuster of Japanese Utility Model Publication No. H7-6036, however, a projection shaft 125 fixing to the anchor 123 is formed with the slider 121 as an integral part, thereby making the slider 121 complex. In addition, the projection shaft 125 supports not only the anchor 123 but also a slide plate 118, thereby making the projection shaft 125 also complex. This makes the cost of the slider 121 high. It is conceivable that the projection shaft 125 is placed by a bolt such as an anchor bolt 104 of the Japanese Patent Publication No. S63-48734 to solve such problems. However, in this case also, the bolt must supports the anchor 123 and the slide plate 118 so that the configuration should be complex and the cost should be still high.
In addition, since the projection shaft 125 supports the anchor 123 and the slide plate 118, the projection shaft 125 must be designed to be long in the longitudinal direction. Therefore, the problem that the webbing height adjuster must be thick is still remained.
Moreover, through Japanese Utility Model Publication No. H7-6036 does not disclose structure between the slide lock mechanism and the release lever 120, it is conceivable that the mechanical structure for transmitting the pivot movement of the release lever 120 to the slide lock mechanism is complex.